1. Field of the Invention
The present invention relates to a board-wiring fault detection device formed on a printed-substrate or a print-circuit board for detecting a fault of wirings for connecting a microcomputer and peripheral devices formed on the print-circuit board.
2. Description of the Prior Art
Conventionally, in electronic devices using or incorporating a microcomputer, a microcomputer and peripheral devices are formed on a printed substrate and then wirings are formed in order to electrically connect the microcomputer with the peripheral devices.
For example, there are following conventional techniques (1) to (3) as fault detection devices for detecting a fault of a device by using a microcomputer:
(1) Japanese laid-open publication number JP-A-60/116040 discloses a conventional technique in which the operation flow enters a normal processing operation after the state of a data processing device is detected by checking whether a fault detection signal is in a set state or in a reset state;
(2) Japanese laid-open publication number JP-A-7/311695 disclosed a technique in which a runaway of a microcomputer is detected based on a reset-signal generation decision method by comparing a general purpose timer with a CPU timer; and
(3) Japanese laid-open publication number JP-A-8/123704 disclosed a technique in which a reset operation is executed when an abnormal operation occurs and is detected, and then an automatic-return decision means checks whether an automatic-return operation is to be processed or not.
As described above, a microcomputer is electrically connected to various peripheral devices through wirings in the conventional techniques. However, there are no devices to automatically detect a board-wiring fault after a reset-signal is released. Therefore, there is a possibility to use an electrical device having a board-wiring fault because it is impossible to detect the fault of the board-wiring in the electrical device. In this case, there is a drawback in the conventional techniques that the microcomputer connected to peripheral devices through board-wirings causes problems such as runaway of a program, destruction of a program, and the like.